236 FRANZ BOLL. 



/3'. Tentacles in a single cycle. — Orinia} 



I propose tlie generic name of Panceria in compliment to 

 the distinguished Professor Panceri, of the University of 

 Naples. The following are the characters : 



Panceria, g. n. — Coenecium in juventute tantum existens, 

 saxis adnatum, tenue, parvum, expansum. Polypi liberi, 

 erecti ; pariete corporis crassa ; tentarulis biserialibus ; peri- 

 stomo parvo, veloque carente ; lamellis mesentericis inferne 

 lobatis, varioque modo coalescentibus. 



Panceria spongiosa, sp. n. — Port Natal. Length, four 

 centim.; diameter, six millim.; tentacles forty- two; peri- 

 stome smooth. 



The specimens examined were placed at my disposal by 

 the generosity of my respected teacher, Professor Leuckart, 

 of Leipsic, who also suggested their investigation. 



Contributions to the Physiology of Vision and of the 

 Sensation of Colour. By Professor Franz Boll, 

 Rome. (' Monatsbericht d. k. Akad. d. Wissensch. zu 

 Berlin/ 11th January and 15th February, 1877.) 



I. 



Experiments on the colour of the retina^ in frogs, and the 

 changes produced in it by white and coloured light, have 

 yielded the following results : 



^ Decliassaing e Miclielotti, ' Mem. Acad. Torino,' xix ; new genus, 

 ^ In my first communication ' On the Anatomy and Physiology of the 

 Hetina ' (this Journal, April, 1877) I mentioned various earlier observa- 

 tions on the red colour of the retinal elements in Invertebrata. But it 

 Lad escaped me tiiat Leydig, nearly a quarter of a century ago, had also 

 observed the red colour of the retiua in frogs and other Amphibia ; and 

 that even the satiny lustre of the dying retina of the frog had not escaped 

 him. His observations are to be found in ' Miiller's Arcliiv fiir Anatomie 

 und Physiologic,' 1853, p. 8 ; in his 'Lehrbuch der Histologie des Men- 

 schen und der Tbiere' (Frankfort, 1857, pp. 238 and 250), and in his paper 

 " Das Auge der Gliederthiere " (Tiibingen, 1864, p. 23). That these ob- 

 servations have attracted so little attention, and have remained barren so 

 far as the doctrine of vision is concerned, is explained by the fact that, in 

 the first place, Leydig does not recognise the red colour of the retina as a 

 general character of this membrane, but believes that he has described 

 only a peculiarity of certain retinae, such as are the coloured oil-drops in 

 the retina of other animals; and that, secondly, the relation of the red 

 pigment to the illumination of the retina has altogether escaped him. 



